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chrome/browser/file_path_watcher.h

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This module provides a way to monitor a file or directory for changes.
-
-#ifndef CHROME_BROWSER_FILE_PATH_WATCHER_H_
-#define CHROME_BROWSER_FILE_PATH_WATCHER_H_
-#pragma once
-
-#include "base/basictypes.h"
-#include "base/file_path.h"
-#include "base/ref_counted.h"
-#include "chrome/browser/browser_thread.h"
-
-// This class lets you register interest in changes on a FilePath.
-// The delegate will get called whenever the file or directory referenced by the
-// FilePath is changed, including created or deleted. Due to limitations in the
-// underlying OS APIs, spurious notifications might occur that don't relate to
-// an actual change to the watch target.
-class FilePathWatcher {
- public:
-  // Declares the callback client code implements to receive notifications. Note
-  // that implementations of this interface should not keep a reference to the
-  // corresponding FileWatcher object to prevent a reference cycle.
-  class Delegate : public base::RefCountedThreadSafe<Delegate> {
-   public:
-    virtual ~Delegate() {}
-    virtual void OnFilePathChanged(const FilePath& path) = 0;
-    // Called when platform specific code detected an error. The watcher will
-    // not call OnFilePathChanged for future changes.
-    virtual void OnError() {}
-  };
-
-  FilePathWatcher();
-  ~FilePathWatcher();
-
-  // Register interest in any changes on |path|. OnPathChanged will be called
-  // back for each change. Returns true on success.
-  bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;
-
-  // Used internally to encapsulate different members on different platforms.
-  class PlatformDelegate
-      : public base::RefCountedThreadSafe<PlatformDelegate,
-                                          BrowserThread::DeleteOnFileThread> {
-   public:
-    virtual ~PlatformDelegate() {}
-
-    // Start watching for the given |path| and notify |delegate| about changes.
-    virtual bool Watch(const FilePath& path, Delegate* delegate)
-        WARN_UNUSED_RESULT = 0;
-
-    // Stop watching. This is called from FilePathWatcher's dtor in order to
-    // allow to shut down properly while the object is still alive.
-    virtual void Cancel() {}
-  };
-
- private:
-  scoped_refptr<PlatformDelegate> impl_;
-
-  DISALLOW_COPY_AND_ASSIGN(FilePathWatcher);
-};
-
-#endif  // CHROME_BROWSER_FILE_PATH_WATCHER_H_